SelectedSelectionKeySet.java throw UnsupportedOperationException

[monkey1993]

Expected behavior

When I use reflection to get a obejct that contains all fields, and then, I input it's info when I iterate it . But,I find an error that is UnsupportedOperationException

Actual behavior

Steps to reproduce

Minimal yet complete reproducer code (or URL to code)

class SelectedSelectionKeySet.java
at line 62

Netty version

4.1.27

JVM version (e.g. java -version)

8u172

OS version (e.g. uname -a)

win7

[normanmaurer]

@monkey1993 please share the code that you used.

[monkey1993]

No code. Just see SelectedSelectionKeySet.java at line 62

[normanmaurer]

@monkey1993 sure but why you even access this SelectedSelectionKeySet ? I mean its internal and we not expose it at all.

[monkey1993]

Reflection to get a object that contains all fields.Analyze memory footprin.

[monkey1993]

Calculate each ChannelHandlerContext to occupy memory.

[normanmaurer]

@monkey1993 I still dont get why you need this... just take an heap-dump and use a heap-dump analyser. I mean I can implement iterator but I am really not sure why you try to hand-roll this stuff.

[monkey1993]

Calculate objects and their subobjects to occupy memory.

[normanmaurer]

yeah and this is exactly what a heap-dump will give you and can be accessed via a heap-dump analyser like eclipse mat.

[monkey1993]

like this

public class Session {
private ChannelHandlerContext ctx;
private long lastActiveTime;
private volatile boolean connect;
private volatile boolean isLogin;
private int sessionId;
}

Calculate this object to occupy memory.

[monkey1993]

it's will be---> _make(8) + long(8) + int(4) + boolean(1) + boolean(1) + ref(4) + padding(6) = 32byte. But no ChannelHandlerContext object is calculated.

[normanmaurer]

@monkey1993 while I still not understand why you bother handrolling a memory profiler I did the changes as it was trivial to fix:

#8244

PTAL

[monkey1993]

I need to estimate the memory footprint of each object to make sure how many people my system can hold, and how it can expand when it expands.

[monkey1993]

As you said, that's trivial, and I can still circumvent it to figure out how much memory an object occupies.